This invention relates to a method and apparatus for controlling and monitoring vehicular hydraulic brake slip control devices supplied with energy from an external source, wherein hydraulic pressure is transmitted to the brake wheel cylinders via at least one static brake circuit and/or at least one dynamic brake circuit, and wherein in the event of a control action taking place fluid flow is admitted from a dynamic circuit into the static brake circuit. Apparatus to implement this method is also claimed as part of this invention.
Brake slip control devices are well known. In such devices electromagnetically or hydraulically actuated valves which inhibit the fluid passage in the event of a pressure failure in the external energy supply system, are inserted in the connecting lines providing hydraulic fluid flow to the prechamber of the master cylinder and thence to the static circuits. Valves are also positioned in the pressure fluid return line from pressure reducing valves to a pressure compensating reservoir (German published patent applications DE-OS No. 3,040,561 filed in the U.S. as patent application Ser. No. 315,819 on Oct. 28, 1981, now U.S. Pat. No. 4,415,210 and DE-OS No. 3,040,562 filed in the U.S. as patent application Ser. No. 316,153 on Oct. 28, 1981, now U.S. Pat. No. 4,416,491). On a failure of the external energy, these valves act to prevent the static circuits from reaching an empty condition and also act to prevent an excessive amount of hydraulic fluid flow from reaching the compensating reservoirs.
A disadvantage of these known devices arises in that these valves will not respond to a defect in the brake valve as long as the pressure in the external energy supply system is maintained.